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The Washington State Department of Health (DOH) has prepared this health consultation at therequest of the Washington State Department of Ecology (Ecology), to evaluate the potential humanhealth risks associated with residents living near a petroleum bulk supply terminal.

The facility was established in the 1950s, as Unocal 76 Products Company, until it became Tosco Distributing Company in March of 1997.1 The plant is currently known as Apple Valley Fuel Company, Inc., and is located in a mixed residential/commercial area of Yakima, Washington (Figure 1). The site is paved and fenced, and consists of an office, warehouse, an aboveground tank farm with four 20,000 gallon and three 10,000 gallon storage tanks, and a pumping station with dispensers (Figure 2). Trucks are used to transport petroleum products to and from the facility.

A site assessment, performed in October 1997, found petroleum hydrocarbons in soil and groundwater.2 Diesel fuel in soil ranged from 27.5 to 820 ppm, heavy oil was detected between 26.7 and 3440 ppm, and gasoline was detected as high as 166 ppm. There has been no soil removal or cleanup of this site, however, two additional assessments performed in March and April 1999, showed no contamination in soil.

During the March assessment, free product (petroleum products) was found in three monitoringwells as a result of a sub-surface spill.1 There was no free product found in monitoring wells in April1999. The most recent groundwater sampling, performed in November 2000, continues to show oneor more BETX compounds and/or the sum of gasoline, diesel, and lube oil-range hydrocarbonsexceeding MTCA Method A cleanup levels in samples from two monitoring wells (MW-3 and MW-5). These wells are located near the above ground tank farm (Figure 2).3

Shallow groundwater, also known as the surface aquifer, usually travels southeast, but sometimes travels northeast. Ecology determined that the surface aquifer is 14 feet below ground surface and was contaminated with gasoline at levels presented in Table 1 below.1

Table 1.

Contaminants of concern detected in on-site groundwater monitoring wells at the Apple Valley Fuel site located in Yakima, WA (Sampling from March through September 2000)

In 1991, Ecology identified nine drinking water wells within one-half mile of the facility (Figure 1).No information was located for these wells regarding sampling, depth, or concentrations. However,most of the wells are either upgradient or cross gradient of any potential TPH plumes.4 Oneexception is an industrial well located one-half mile southwest (downgradient) from the site. Thiswell is screened within a deeper, confined aquifer beneath the surface aquifer.1 A site visit,performed by DOH on March 6, 2001, revealed no private domestic wells within a two block areaof site. Discussions with Ecology and local health indicated that all domestic wells described inFigure 1 are believed to be closed since this area has been hooked up to city water. However, asurvey of all houses and businesses out to a half-mile radius of the site has not been performed.

DISCUSSION

Site environmental sampling data were screened using federal (ATSDR and EPA), and state (MTCA method B) health-based criteria (comparison values). Comparison values are media-specific concentrations used to select environmental contaminants for further evaluation. Contaminant concentrations below comparison values are unlikely to pose a health threat, and were not further evaluated in this health consultation. Contaminant concentrations exceeding comparison values (Table 1) do not necessarily pose a health threat, but were further evaluated as contaminants of concern to determine whether they are at levels which could result in adverse human health effects.

Groundwater levels in October are higher than in March due to irrigation in the summer and fall. The raising and lowering of groundwater causes a "smear zone," in which contamination is saturated by groundwater during the high groundwater season. This contamination is then "smeared" in the soil as the aquifer drops in the winter. This phenomenon may explain why free product has not been found in monitoring wells during winter sampling of wells from which free product has already been removed.1

On-site groundwater monitoring wells near the above ground storage tanks contain TPH at levels above health comparison values. Other on-site wells located downgradient to the south and southeast were not contaminated, indicating that contaminated groundwater is not moving off site in that direction. Although groundwater can move northeast, it is unlikely that contaminants will travel offsite in this direction since the predominant flow is southeast. However, there is no way to verify this without locating an existing drinking water or irrigation well, or installing a monitoring well northeast of MW-3 (Figure 2).

In addition, there is no data to indicate that the deep water aquifer has not been contaminated.

EXPOSURE PATHWAYS AND CHILDREN

ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants and children deserve special emphasis with regard to exposures to environmental contaminants. Infants, young children, and the unborn may be at greater risk than adults from exposure to particular contaminants. Exposure during key periods of growth and development may lead to malformation of organs (teratogenesis), disruption of function, and even premature death. In certain instances, maternal exposure, via the placenta, could adversely effect the unborn child.

After birth, children may receive greater exposures to environmental contaminants than adults. Children are often more likely to be exposed to contaminants from playing outdoors, ingesting food that has come into contact with hazardous substances, or breathing soil and dust. Pound for pound body weight, children drink more water, eat more food, and breathe more air than adults. For example, in the United States, children in the first 6 months of life drink 7 times as much water per pound as the average adult. The implication for environmental health is that, by virtue of children's lower body weight, given the same exposures, they can receive significantly higher relative contaminant doses than adults.

It is unlikely that children are being exposed to the contaminants in soil because the site is fenced. Children are not likely to be exposed to contaminants in groundwater because groundwater doesn't appear to be leaving the site, and residential homes in this area are using Yakima City water.

CONCLUSIONS

Groundwater contamination at the Apple Valley Fuel site represents a no apparent public health hazard because there does not appear to be any drinking water wells in the vicinity of the site.

Groundwater contamination originating from the Apple Valley Fuel site does not appear to be moving off-site. Site related contaminants have not been detected in monitoring wells located southeast of the groundwater contaminant plume. Since groundwater flows predominantly to the southeast, contaminants are not likely to be moving off site.. However, available data indicate that groundwater can, to lesser extent, move northeast. Since there are no monitoring wells to the northeast of the existing plume, movement of contaminants in this direction can not be discounted.

Contaminated soil found at the Apple Valley Fuel site represents a no apparent public health hazard . Although soil contaminated with TPH has been found in several areas, access to the site is limited by a fence.

RECOMMENDATIONS/PUBLIC HEALTH ACTION PLAN

Although contaminated groundwater beneath the site does not appear to be moving off-site, periodic groundwater monitoring should continue for further verification. An existing well should be located or another monitoring well should be installed northeast of MW-3 and sampled for petroleum related contaminants to ensure that groundwater contamination is not moving off-site in this direction.

This Health Consultation was prepared by the Washington State Department of Health under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was begun.

Debra GableTechnical Project OfficerSPS, SSAB, DHACATSDR

The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.